An ethyne-pyridyl organic polymer photocatalyst and a preparation method and application thereof

Abstract

The application relates to the technical field of photocatalytic material preparation, in particular to a preparation method of an ethyne-pyridyl organic polymer photocatalyst and application of the photocatalytic preparation of H2O2. The ethyne-pyridyl organic polymer material takes pyridyl N as a water molecule activation center and an alkynyl group as a redox center, and is an ethyne-pyridyl organic polymer material with a specific energy band structure and an active center. When H2O2 is prepared through photocatalysis, the electron donating / absorbing property of a substituent group is utilized, the meta-substituent group of the pyridyl N is changed, the electron cloud density of the pyridyl N is regulated, the hydrogen bond force between a water molecule and N is adjusted, the O-H bond length of the water molecule is lengthened, the oxidation of H2O to generate a proton and oxygen is promoted, and the consumption of photo-generated holes is accelerated. The oxygen reduction path is coupled, so that the overall photocatalytic H2O2 generation efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic material preparation technology, specifically to a method for preparing an acetylene-pyridine-based organic polymer photocatalyst and its application in the photocatalytic preparation of H2O2. Background Technology

[0002] Hydrogen peroxide (H2O2) is an important green oxidant widely used in chemical, environmental protection, and medical fields. To meet the growing market demand, large-scale production of H2O2 has become crucial. Currently, the main industrial synthesis method for H2O2 is the anthraquinone oxidation process. However, this method has many drawbacks, such as high energy consumption, reliance on toxic organic solvents, and the generation of large amounts of waste. These problems not only have a serious impact on the environment but also impose an economic burden. Therefore, developing green and efficient methods for producing H2O2 is urgently needed.

[0003] Solar-powered synthesis of water (H2O) and oxygen (O2) into H2O2 is a green and safe method, considered the most promising alternative to the traditional anthraquinone process. In recent years, to further explore the potential of photocatalytic reactions and improve the efficiency of H2O2 production, researchers have developed various types of semiconductor photocatalysts. These photocatalysts mainly include inorganic metal-based photocatalysts (metal oxides, metal sulfides) and organic polymer-based photocatalysts (polymerized carbonitrides, covalent triazine frameworks, and porous organic polymers). Among them, porous organic polymers, with their extended π-conjugation, broad light absorption capacity, and abundant active sites, have attracted widespread attention. Porous organic polymers have demonstrated excellent photocatalytic H2O2 production efficiency through oxygen reduction reaction (ORR) and water oxidation reaction (WOR). However, water oxidation, a key step in photocatalytic H2O2 production, suffers from low efficiency, severely restricting the overall reaction kinetics and significantly limiting the overall photocatalytic H2O2 production efficiency.

[0004] In the photocatalytic preparation of H2O2, water reacts with photogenerated holes (h + They combine to produce oxygen (O2) and protons (H). + These substances then act as reactants in the ORR reaction. Oxygen reacts with photogenerated electrons (e... − ) combine to form superoxide radicals (•O2). − The latter further connected with H + The photogenerated holes combine to form H₂O₂. It is noteworthy that the photogenerated hole recombining (WOR) step is the rate-determining step in photocatalytic H₂O₂ production, primarily because the potential of WOR is significantly higher than that of ORR. The slow kinetics of WOR lead to a reduced consumption rate of photogenerated holes, which in turn results in the recombination of photogenerated carriers, thus significantly reducing the efficiency of photocatalytic H₂O₂ production. Furthermore, due to the slow kinetics of WOR, H₂O₂...+ The low generation rate of H2O2 further reduces the efficiency of H2O2 production via the ORR pathway. Notably, the porous wall structure of hollow nanotubes facilitates mass transport, increasing the accessibility of active sites to O2 and water molecules, thereby promoting efficient H2O2 generation. Therefore, designing and preparing porous organic polymers (POPs) with hollow nanotube structures rich in water oxidation active sites, while optimizing the WOR (Work-Oriented Reaction) structure, is crucial for improving the overall rate of H2O2 photocatalytic production. Pyridine-based organic polymer photocatalysts have received considerable attention and have been extensively studied in the photocatalytic production of H2O2. However, the water oxidation kinetics of pyridine-based organic polymer photocatalysts remain relatively slow, resulting in low photocatalytic H2O2 production efficiency. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, the present invention aims to provide an acetylene-pyridine-based organic polymer photocatalyst, its preparation method, and its applications. By altering the meta-substituent of pyridine N, the interaction force between pyridine N and water molecules is modulated, promoting water oxidation kinetics and accelerating the consumption of photogenerated holes, thereby improving the overall photocatalytic H2O2 generation efficiency. The regulation of the microenvironment of the organic polymer photocatalyst plays a crucial role in enhancing the performance of photocatalytic H2O2 production.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for preparing an acetylene-pyridyl organic polymer photocatalyst includes the following steps: A solid-liquid mixture was obtained by adding a pyridyl compound, 1,1,2,2-tetra(4-ethylphenyl)ethylene, copper iodide, and palladium(II) dichloride of bis(triphenylphosphine) to a solvent.

[0007] The solid-liquid mixture then undergoes a Sonogashira coupling reaction to prepare an acetylene-pyridyl organic polymer photocatalyst.

[0008] The electron-donating substituent at the N-me position of the pyridyl compound is methyl, acyloxy, amino, hydroxy, or methoxy, and the electron-withdrawing substituent is carboxyl, sulfonic acid, cyano, nitro, or trifluoromethyl.

[0009] In a preferred embodiment of the present invention, the substituent at the N-me position of the pyridyl compound is an electron-donating methyl substituent.

[0010] In a preferred embodiment of the present invention, the molar ratio of the pyridyl compound, 1,1,2,2-tetra(4-ethylphenyl)ethylene, copper iodide and palladium(II) dichloride is 2:1~1.5:0.4~0.5:0.2~0.25.

[0011] In a preferred embodiment of the present invention, the solvent is a mixed solution of toluene and triethylamine, wherein the volume ratio of the mixed solution of toluene and triethylamine is 1:2~5.

[0012] In a preferred embodiment of the present invention, the Sonogashira coupling reaction of the solid-liquid mixture occurs at a temperature of 100°C to 110°C for 3 to 7 days.

[0013] In a preferred embodiment of the present invention, the post-reaction treatment involves repeated washing and filtration, followed by Soxhlet extraction for purification, and finally drying under vacuum conditions. The washing agents for repeated washing are water, methanol, and N,N-dimethylformamide.

[0014] Another object of the present invention is to provide an acetylene-pyridine-based organic polymer photocatalyst prepared by any of the above preparation methods, wherein the photocatalyst has a hollow nanotube porous wall structure.

[0015] The application of the organic polymer photocatalyst described in this invention in the field of photocatalytic synthesis of H2O2.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention synthesizes an acetylene-pyridine-based organic polymer photocatalyst via a Sonogashira coupling reaction using pyridine compounds and 1,1,2,2-tetra(4-ethylphenyl)ethylene as raw materials. It provides an acetylene-pyridine-based organic polymer photocatalyst, its preparation method, and its applications. By changing the substituents of meta-pyridine N (electron-donating substituents are methyl, acyloxy, amino, hydroxy, methoxy; electron-withdrawing substituents are carboxyl, sulfonic acid, cyano, nitro, trifluoromethyl), the electron-donating / withdrawing properties of different substituents are utilized to alter the hydrogen bonding forces between N and water molecules, thereby enhancing water oxidation kinetics and improving the overall photocatalytic H2O2 generation efficiency. This demonstrates that the microenvironment regulation of the polymer photocatalyst plays a crucial role in improving the overall H2O2 generation efficiency.

[0017] 2. This invention provides an acetylene-pyridine-based organic polymer photocatalyst. The highly conjugated acetylene group in its catalyst framework not only possesses excellent photogenerated electron transport capabilities but also provides abundant active sites for oxygen molecule adsorption. Pyridine is a six-membered aromatic molecule in which the electron-rich nitrogen atom can form strong hydrogen bonds with water molecules. This hydrogen bonding elongates the OH bond length in water molecules, lowers the OH bond energy, and makes the OH bond easier to break, thereby enhancing the kinetics of the water oxidation process.

[0018] 3. The acetylene-pyridine-based organic polymer photocatalyst prepared by this invention has a hollow nanotube porous wall structure, which facilitates the transport of substances and improves the accessibility of active sites to O2 and water molecules, thereby promoting the efficient generation of H2O2.

[0019] 4. The application of the acetylene-pyridine-based organic polymer photocatalyst prepared in this invention in the field of photocatalytic synthesis of H2O2: Its electron-donating substituent methyl group significantly increases the electron density of pyridine N through π-π conjugation and σ-π hyperconjugation effects. This enhanced electron density strengthens the hydrogen bond interaction (N···HO) between its lone pair electrons and water molecules, leading to a significant weakening of the OH bond in water molecules, thereby promoting H2O2 synthesis. + The generation of O2 promotes the consumption of photogenerated holes, ultimately improving the overall efficiency of photocatalytic H2O2 production. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the synthetic route for the acetylene-pyridine-based organic polymer photocatalysts prepared in Example 1 and Comparative Example 1 of the present invention.

[0021] Figure 2 (a) shows the FT-IR spectra of the samples from Example 1 and Comparative Example 1 of the present invention; (b) shows the solid-state spectra of the samples from Example 1 and Comparative Example 1 of the present invention. 13 (c) is the N2 adsorption / desorption isotherm of the samples of Example 1 and Comparative Example 1 of this invention.

[0022] Figure 3 (a) and (b) are transmission electron microscope images of the samples from Example 1 and Comparative Example 1 of the present invention, respectively.

[0023] Figure 4 (a) and (b) are Mott-Schottky plots of the samples from Example 1 and Comparative Example 1, respectively; (c) is the bandgap curve of the samples from Example 1 and Comparative Example 1, respectively; and (d) is the electronic band diagram of the samples from Example 1 and Comparative Example 1, respectively.

[0024] Figure 5 (a) shows the H2O2 production curves of the samples of Example 1 and Comparative Example 1 of the present invention; (b) compares the photocatalytic H2O2 generation performance of the sample of Example 1 of the present invention with that reported in the literature.

[0025] Figure 6 (a) shows the electrostatic potential diagrams of the samples of Example 1 and Comparative Example 1 of the present invention; (b) shows the interaction between water molecules and the samples of Example 1 and Comparative Example 1 calculated by density functional theory (DFT). Detailed Implementation

[0026] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0028] Example 1 A method for preparing an acetylene-pyridyl organic polymer photocatalyst CH3-TEE-POP includes the following steps: (1) Add 0.8 mmol of 2,5-dibromo-3-methylpyridine, 0.4 mmol of 1,1,2,2-tetra(4-ethylphenyl)ethylene, 0.16 mmol of copper iodide and 0.08 mmol of bis(triphenylphosphine)palladium(II) chloride to a Schlenk reaction flask, followed by the addition of a mixed solution of 4 mL toluene and 8 mL triethylamine to form a solid-liquid mixture.

[0029] (2) The solid-liquid mixture was then transferred to a Schlenk reaction tube for five freeze-thaw cycles. Under nitrogen protection, the reaction tube was placed in an oil bath at 105 °C for three days to form a precipitate.

[0030] (3) The precipitate was repeatedly washed with water, methanol and N,N-dimethylformamide to remove impurities, and then further purified by Soxhlet extraction with a 1:1 dichloromethane-ethanol mixture. Finally, it was dried under vacuum to obtain the acetylene-pyridine-based organic polymer photocatalyst CH3-TEE-POP.

[0031] Example 2 A method for preparing an acetylene-pyridyl organic polymer photocatalyst CH3-TEE-POP includes the following steps: (1) Add 0.8 mmol of 2,5-dibromo-3-methylpyridine, 0.52 mmol of 1,1,2,2-tetra(4-ethylphenyl)ethylene, 0.18 mmol of copper iodide and 0.092 mmol of bis(triphenylphosphine)palladium(II) chloride to a Schlenk reaction flask, followed by the addition of a mixed solution of 4 mL toluene and 12 mL triethylamine to form a solid-liquid mixture.

[0032] (2) The solid-liquid mixture was then transferred to a Schlenk reaction tube for five freeze-thaw cycles. Under nitrogen protection, the reaction tube was placed in an oil bath at 100 °C for five days to form a precipitate.

[0033] (3) The precipitate was repeatedly washed with water, methanol and N,N-dimethylformamide to remove impurities, and then further purified by Soxhlet extraction with a 1:1 dichloromethane-ethanol mixture. Finally, it was dried under vacuum to obtain the acetylene-pyridine-based organic polymer photocatalyst CH3-TEE-POP.

[0034] Example 3 A method for preparing an acetylene-pyridyl organic polymer photocatalyst CH3-TEE-POP includes the following steps: (1) Add 0.8 mmol of 2,5-dibromo-3-methylpyridine, 0.6 mmol of 1,1,2,2-tetra(4-ethylphenyl)ethylene, 0.16 mmol of copper iodide and 0.08 mmol of bis(triphenylphosphine)palladium(II) chloride to a Schlenk reaction flask, followed by the addition of a mixed solution of 4 mL toluene and 12 mL triethylamine to form a solid-liquid mixture.

[0035] (2) The solid-liquid mixture was then transferred to a Schlenk reaction tube for five freeze-thaw cycles. Under nitrogen protection, the reaction tube was placed in an oil bath at 110 °C for seven days to form a precipitate.

[0036] (3) The precipitate was repeatedly washed with water, methanol and N,N-dimethylformamide to remove impurities, and then further purified by Soxhlet extraction with a 1:1 dichloromethane-ethanol mixture. Finally, it was dried under vacuum to obtain the acetylene-pyridine-based organic polymer photocatalyst CH3-TEE-POP.

[0037] Example 4 A method for preparing an acetylene-pyridyl organic polymer photocatalyst CH3-TEE-POP includes the following steps: (1) Add 0.8 mmol of 2,5-dibromo-3-methylpyridine, 0.52 mmol of 1,1,2,2-tetra(4-ethylphenyl)ethylene, 0.18 mmol of copper iodide and 0.092 mmol of bis(triphenylphosphine)palladium(II) chloride to a Schlenk reaction flask, followed by the addition of a mixed solution of 4 mL toluene and 20 mL triethylamine to form a solid-liquid mixture.

[0038] (2) The solid-liquid mixture was then transferred to a Schlenk reaction tube for five freeze-thaw cycles. Under nitrogen protection, the reaction tube was placed in an oil bath at 110 °C for three days to form a precipitate.

[0039] (3) The precipitate was repeatedly washed with water, methanol and N,N-dimethylformamide to remove impurities, and then further purified by Soxhlet extraction with a 1:1 dichloromethane-ethanol mixture. Finally, it was dried under vacuum to obtain the acetylene-pyridine-based organic polymer photocatalyst CH3-TEE-POP.

[0040] Example 5 A method for preparing an acetylene-pyridyl organic polymer photocatalyst CH3-TEE-POP includes the following steps: (1) Add 0.8 mmol of 2,5-dibromo-3-methylpyridine, 0.4 mmol of 1,1,2,2-tetra(4-ethylphenyl)ethylene, 0.16 mmol of copper iodide and 0.08 mmol of bis(triphenylphosphine)palladium(II) chloride to a Schlenk reaction flask, followed by the addition of a mixed solution of 4 mL toluene and 16 mL triethylamine to form a solid-liquid mixture.

[0041] (2) The solid-liquid mixture was then transferred to a Schlenk reaction tube for five freeze-thaw cycles. Under nitrogen protection, the reaction tube was placed in an oil bath at 100 °C for seven days to form a precipitate.

[0042] (3) The precipitate was repeatedly washed with water, methanol and N,N-dimethylformamide to remove impurities, and then further purified by Soxhlet extraction with a 1:1 dichloromethane-ethanol mixture. Finally, it was dried under vacuum to obtain the acetylene-pyridine-based organic polymer photocatalyst CH3-TEE-POP.

[0043] Example 6 A method for preparing an acetylene-pyridyl organic polymer photocatalyst CH3-TEE-POP includes the following steps: (1) Add 0.8 mmol of 2,5-dibromo-3-methylpyridine, 0.6 mmol of 1,1,2,2-tetra(4-ethylphenyl)ethylene, 0.2 mmol of copper iodide and 0.1 mmol of bis(triphenylphosphine)palladium(II) chloride to a Schlenk reaction flask, followed by the addition of a mixed solution of 4 mL toluene and 20 mL triethylamine to form a solid-liquid mixture.

[0044] (2) The solid-liquid mixture was then transferred to a Schlenk reaction tube for five freeze-thaw cycles. Under nitrogen protection, the reaction tube was placed in an oil bath at 110 °C for seven days to form a precipitate.

[0045] (3) The precipitate was repeatedly washed with water, methanol and N,N-dimethylformamide to remove impurities, and then further purified by Soxhlet extraction with a 1:1 dichloromethane-ethanol mixture. Finally, it was dried under vacuum to obtain the acetylene-pyridine-based organic polymer photocatalyst CH3-TEE-POP.

[0046] Comparative Example 1 A method for preparing an acetylene-pyridyl organic polymer photocatalyst NO2-TEE-POP includes the following steps: (1) Add 0.8 mmol of 2,5-dibromo-3-nitropyridine, 0.4 mmol of 1,1,2,2-tetra(4-ethylphenyl)ethylene, 0.16 mmol of copper iodide and 0.08 mmol of bis(triphenylphosphine)palladium(II) chloride to a Schlenk reaction flask, followed by the addition of a mixed solution of 4 mL toluene and 8 mL triethylamine to form a solid-liquid mixture.

[0047] (2) The solid-liquid mixture was then transferred to a Schlenk reaction tube for five freeze-thaw cycles. Under nitrogen protection, the reaction tube was immersed in an oil bath at 105 °C for three days to form a precipitate.

[0048] (3) The precipitate was repeatedly washed with water, methanol and N,N-dimethylformamide to remove impurities, and then further purified by Soxhlet extraction with a 1:1 dichloromethane-ethanol mixture. Finally, it was dried under vacuum to obtain the organic polymer photocatalyst NO2-TEE-POP containing ethynylpyridinyl groups.

[0049] Results Analysis Pyridine-derived compounds exhibit unique photoelectric properties and are widely used as structural units for constructing high-performance photocatalytic polymers. Through Sonogashira coupling reactions (such as...) Figure 1 A bright orange pyridine-acetylene organic polymer (CH3-TEE-POP) was synthesized using 2,5-dibromo-3-methylpyridine and 1,1,2,2-tetra(4-ethynylphenyl)ethylene (TEE) as raw materials. To investigate the effect of changing the meta-substituent at the nitrogen position of pyridine on water oxidation kinetics and photocatalytic H2O2 production efficiency, 2,5-dibromo-3-methylpyridine was replaced with 2,5-dibromo-3-nitropyridine, resulting in a deep red control sample, NO2-TEE-POP.

[0050] Figure 2 (a) shows the FT-IR spectra of the samples from Example 1 and Comparative Example 1 of the present invention; (b) shows the solid-state spectra of the samples from Example 1 and Comparative Example 1 of the present invention. 13 (c) is the N2 adsorption / desorption isotherm of the samples of Example 1 and Comparative Example 1 of this invention. Figure 2As shown in (a), no ≡CH bond vibration signal peak (3283 cm⁻¹) originating from 1,1,2,2-tetra(4-ethynylphenyl)ethylene was detected in the FTIR spectra of CH₃-TEE-POP and NO₂-TEE-POP. -1 This indicates that 1,1,2,2-tetra(4-ethynylphenyl)ethylene reacted successfully with 2,5-dibromo-3-methylpyridine and 2,5-dibromo-3-nitropyridine, respectively. Figure 2 Figure (b) shows that in the solid state of CH3-TEE-POP and NO2-TEE-POP 13 The C10 NMR spectrum showed signal peaks for C≡C carbon atoms, located at 96 ppm and 83 ppm, respectively. Notably, in CH3-TEE-POP... 13 In the C NMR spectrum, the carbon signal peak of the methyl group appeared at 16 ppm, which confirms that the pyridyl group was successfully introduced into the skeleton of CH3-TEE-POP and NO2-TEE-POP. The above results indicate that CH3-TEE-POP of Example 1 and NO2-TEE-POP of Comparative Example 1 have been successfully prepared. Figure 2 The results in (c) show that CH3-TEE-POP and NO2-TEE-POP exhibit mixed characteristics of type I and type IV isotherms. In the low-pressure region (P / P0<0.01), the nitrogen adsorption capacity increases rapidly, while in the high-pressure region (P / P0>0.8), a hysteresis phenomenon is observed. This indicates that CH3-TEE-POP and NO2-TEE-POP contain a large number of micropores and mesopores. This hierarchical porous structure reduces the diffusion distance of substrate molecules and promotes the rapid transport of reactants to active sites, thereby significantly improving the photocatalytic yield of H2O2.

[0051] Figure 3 Images (a) and (b) are transmission electron microscope images of samples from Example 1 and Comparative Example 1 of the present invention, respectively. Figure 3 Images (a) and (b) show that CH3-TEE-POP and NO2-TEE-POP have a hybrid morphology consisting of hollow nanotubes and spheres. The porous wall structure of the hollow nanotubes facilitates the transport of substances and improves the accessibility of active sites to O2 and water molecules, thereby promoting the efficient generation of H2O2.

[0052] Figure 4 (a) and (b) are Mott-Schottky plots of the samples from Example 1 and Comparative Example 1, respectively; (c) is the bandgap curve of the samples from Example 1 and Comparative Example 1, respectively; and (d) is the electronic band diagram of the samples from Example 1 and Comparative Example 1, respectively. Figure 4Tables (a) and (b) show the Mott-Schottky plots of CH3-TEE-POP and NO2-TEE-POP, with conduction band potentials of -0.53V and -0.57V, respectively. Figure 4 In (c), the optical band gaps of CH3-TEE-POP and NO2-TEE-POP were approximately 2.18 eV and 1.97 eV, respectively. The wider band gap observed in CH3-TEE-POP may be due to the electron-donating effect of the meta-methyl group, which partially offsets the electron-attracting effect of the pyridine nitrogen through σ delocalization. Figure 4 In the middle (d) sample, the valence band (VB) potentials of CH3-TEE-POP and NO2-TEE-POP are 1.65V and 1.40V (relative to NHE), respectively. Both values ​​are below 1.76V but above 1.23V, which confirms that the 2-electron WOR generated by H2O2 is thermodynamically infeasible, while the oxidation of water to O2 and H2O is possible. + It is still feasible, generating O2 and H + It can be used as a reactant to generate H2O2.

[0053] Figure 5 (a) shows the H2O2 production curves of the samples from Example 1 and Comparative Example 1 of this invention; (b) is a comparison graph of the photocatalytic H2O2 generation performance of the sample from Example 1 of this invention with that reported in the literature. The photocatalytic H2O2 production performance of CH3-TEE-POP and NO2-TEE-POP was studied in a pure water and oxygen environment under visible light irradiation (wavelength ≥ 400 nm) and room temperature conditions, without the addition of any external substances. Figure 5 As shown in (a), with the extension of visible light irradiation time, the amount of H2O2 generated by CH3-TEE-POP and NO2-TEE-POP gradually increased. Within the first 30 minutes of irradiation, CH3-TEE-POP exhibited an excellent photocatalytic H2O2 generation rate, reaching 3183 μmol / g·h, which is superior to most previously reported photocatalysts. Figure 5 (b) In contrast, NO2-TEE-POP, under the same conditions, exhibited a photocatalytic H2O2 generation rate of only 1609 μmol / g·h. The superior photocatalytic performance of CH3-TEE-POP compared to NO2-TEE-POP is mainly attributed to the electron-donating effect of the meta-methyl group on the pyridine nitrogen heterocycle. The introduction of the electron-donating methyl group significantly increases the electron density of pyridine N. This enhanced electron density strengthens the hydrogen bond interaction (N···HO) between its lone pair electrons and water molecules, lengthening the OH bonds in water molecules, thereby promoting H2O2 generation. +This process promotes the generation of O2. Simultaneously, it facilitates the consumption of photogenerated holes, ultimately improving the efficiency of photocatalytic H2O2 production. After 3 hours of continuous illumination, the H2O2 production of CH3-TEE-POP and NO2-TEE-POP reached 5.07 mmol / L and 3.06 mmol / L, respectively.

[0054] Figure 6 (a) shows the electrostatic potential diagrams of the samples of Example 1 and Comparative Example 1 of the present invention; (b) shows the interaction between water molecules and the samples of Example 1 and Comparative Example 1 calculated by density functional theory (DFT). Figure 6 The electrostatic potential in (a) shows that changes in the meta-substituent of pyridine N alter the charge distribution in CH3-TEE-POP and NO2-TEE-POP. Compared to NO2-TEE-POP, the electron-donating substituent at the meta-position of pyridine N in CH3-TEE-POP increases the charge density of N. Figure 6 The results in (b) show that the interaction between N and water molecules is stronger in CH3-TEE-POP than in NO2-TEE-POP. This result stems from the fact that the meta-electron-donating methyl group increases the electron cloud density of N, while the electron-withdrawing nitro group decreases it. The higher electron cloud density enhances the interaction between N and water molecules, leading to a more significant weakening of the OH bond in the water molecule. Specifically, the OH bond lengths increased from 0.962 Å to 0.978 Å (CH3-TEE-POP) and 0.973 Å (NO2-TEE-POP), respectively. The longer OH bond lengths favor the four-electron water oxidation reaction (4e⁻ WOR), which generates H₂ by consuming photogenerated holes. + And O2.

[0055] The properties of pyridyl compounds with electron-donating substituents at the N-me position such as methyl, acyloxy, amino, hydroxy, or methoxy, and electron-withdrawing substituents such as carboxyl, sulfonic acid, cyano, nitro, or trifluoromethyl are similar to those in Example 1 and will not be described in detail here.

[0056] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0057] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing an acetylene-pyridyl organic polymer photocatalyst, characterized in that, Includes the following steps: 2,5-Dibromo-3-methylpyridine, 1,1,2,2-tetra(4-ethynylphenyl)ethylene, copper iodide, and palladium(II) dichloride of bis(triphenylphosphine) chloride were added to a solvent to obtain a solid-liquid mixture; Under a protective gas atmosphere, a solid-liquid mixture undergoes a Sonogashira coupling reaction to prepare an acetylene-pyridyl organic polymer photocatalyst.

2. The method for preparing the acetylene-pyridyl organic polymer photocatalyst according to claim 1, characterized in that, The molar ratio of 2,5-dibromo-3-methylpyridine, 1,1,2,2-tetra(4-ethynylphenyl)ethylene, copper iodide, and bis(triphenylphosphine)palladium(II) dichloride is 2:1~1.5:0.4~0.5:0.2~0.

25.

3. The method for preparing the acetylene-pyridyl organic polymer photocatalyst according to claim 1, characterized in that, The solvent is a mixed solution of toluene and triethylamine, wherein the volume ratio of toluene to triethylamine is 1:2~5.

4. The method for preparing the acetylene-pyridyl organic polymer photocatalyst according to claim 1, characterized in that, The Sonogashira coupling reaction of solid-liquid mixtures occurs at temperatures ranging from 100°C to 110°C for 3 to 7 days.

5. The method for preparing the acetylene-pyridyl organic polymer photocatalyst according to claim 1, characterized in that, The post-reaction treatment involved repeated washing and filtration, followed by Soxhlet extraction for purification, and finally drying under vacuum. The washing agents used in the repeated washing were water, methanol, and N,N-dimethylformamide.

6. An acetylene-pyridyl-based organic polymer photocatalyst prepared by the preparation method according to any one of claims 1-5.

7. The application of the acetylene-pyridine-based organic polymer photocatalyst according to claim 6 in the field of photocatalytic synthesis of H2O2.

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